阅读说明：本技术 一种利用加热炉余热对冷锭预热的加热工艺 (Heating process for preheating cold ingot by using waste heat of heating furnace ) 是由 曹启航 涂高岭 张凯亮 徐群 王子君 黑志刚 王欢 范琳璟 于 2021-06-24 设计创作，主要内容包括：本发明涉及一种利用加热炉余热对冷锭进行预热的加热工艺,具体工艺方法如下：选取一台保温性好的加热炉(保温性好是指：此加热炉降温速度一般一小时降温1～5℃)；当上一批次的钢锭锻造结束后趁加热炉余热较高,在一小时内完成冷锭装炉；装炉后,若仪表显示炉温＞950℃,则提起炉门降温(避免钢锭内外温差太大,形成热应力裂纹),台车不拉出,待炉温降至650～950℃,此时不用点火,关闭炉门进行焖炉预热,当焖炉炉温低于500℃时,则点火升温至650～750℃并在此温度下保温1小时,再次熄火后继续焖炉,此过程可以反复执行,直到焖炉至少6小时(6小时含650-750℃保温的1小时在内),焖炉预热结束后开始正常点火升温,执行正常点火加热工艺,与常规加热工艺相比,能节约低温预热阶段的加热能源消耗。(The invention relates to a heating process for preheating a cold ingot by using waste heat of a heating furnace, which comprises the following specific process steps: selecting a heating furnace with good heat preservation (the good heat preservation refers to that the temperature of the heating furnace is reduced by 1-5 ℃ in one hour generally); when the residual heat of the heating furnace is higher after the steel ingots of the previous batch are forged, finishing cold ingot charging within one hour; after furnace loading, if the furnace temperature is more than 950 ℃ displayed by the instrument, lifting the furnace door to cool (avoiding forming thermal stress cracks due to too large temperature difference inside and outside the steel ingot), not pulling out the trolley, when the furnace temperature is reduced to 650-950 ℃, not igniting at the moment, closing the furnace door to perform annealing preheating, when the annealing furnace temperature is lower than 500 ℃, igniting to heat to 650-750 ℃, preserving heat for 1 hour at the temperature, extinguishing again and continuing annealing, wherein the process can be repeatedly executed until the annealing furnace is at least 6 hours (the 6 hours contain 1 hour of 650 plus 750 ℃), normally igniting to heat after annealing, executing a normal ignition heating process, and compared with the conventional heating process, saving the heating energy consumption in the low-temperature preheating stage.)

1. A heating process for preheating a cold ingot by using waste heat of a heating furnace is characterized by comprising the following steps: the specific process method comprises the following steps: selecting a heating furnace with good heat preservation, wherein the good heat preservation means that the temperature of the heating furnace is reduced by 1-5 ℃ per hour; when the residual heat of the heating furnace is high after the steel ingots of the previous batch are forged, finishing cold ingot charging within 1 hour through a trolley; after furnace charging, if the furnace temperature is higher than 950 ℃ displayed by the instrument, lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 650-950 ℃, not igniting, closing the furnace door to smolder, when the smoldering furnace temperature is lower than 500 ℃, igniting and heating to 650-750 ℃, preserving heat for 1 hour at the temperature, extinguishing again and continuing smoldering, wherein the process is repeatedly executed until the smoldering furnace is at least 6 hours and contains 1 hour of heat preservation at 650-750 ℃, starting normal ignition and heating after the smoldering furnace is preheated, and executing a normal ignition and heating process; namely, the temperature is directly raised to the forging temperature at the speed of 80-150 ℃ per hour, and the forging is carried out after the temperature is discharged.

2. The heating process for preheating a cold ingot by using the waste heat of the heating furnace according to claim 1, characterized in that: for the carbon steel of group I steel and the alloy structural steel in group II specified by JB/T6052-1992 standard, when the ingot type is not more than 10 tons and the diameter is not more than phi 1000mm, a trolley type heating furnace with good heat preservation performance is selected, when the steel ingot of the previous batch is forged, the residual heat of the heating furnace is higher, and the cold ingot charging is completed by the trolley within 1 hour; after furnace charging, when the furnace temperature is higher than 950 ℃, only lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 650-950 ℃, starting to close the furnace door, not igniting at the moment, directly using the residual heat of the forged heating furnace to stew, when the temperature of a stew instrument is lower than 500 ℃, starting to ignite again, raising the furnace temperature to 650-750 ℃, keeping the temperature for 1 hour, extinguishing the furnace, continuing to stew, and repeatedly executing the process until the stew furnace is preheated for at least 6 hours, and the stew furnace is kept at 650-750 ℃ for 1 hour; igniting after the annealing, directly heating to the forging temperature at the speed of not more than 150 ℃/H based on the furnace temperature after furnace closing, and taking the blank out of the furnace for forging after normal heat preservation for 1 hour.

3. The heating process for preheating a cold ingot by using the waste heat of the heating furnace according to claim 1, characterized in that: for the carbon steel of group I steel and the alloy structural steel in group II specified by JB/T6052-1992 standard, when the ingot type meets the requirements of more than 10 tons and less than 40 tons and the diameter of a cold ingot is not more than phi 1500mm, before heating, selecting a trolley type heating furnace with good heat preservation performance, and when the forging of the steel ingot of the previous batch is finished, the residual heat of the heating furnace is higher, and the cold ingot charging is finished by the trolley within 1 hour; after furnace charging, when the furnace temperature is higher than 950 ℃, only lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 800-950 ℃, closing the furnace door to execute annealing, not igniting at the moment, directly using the residual heat of the forged heating furnace to perform annealing, when the annealing instrument temperature is lower than 500 ℃, igniting again, heating the furnace temperature to 650-750 ℃, keeping the temperature for 1 hour, extinguishing the furnace, continuing the annealing, repeatedly executing the process until the annealing is preheated for at least 6 hours, keeping the temperature for 1 hour including the ignition of 650-750 ℃, taking the temperature after the annealing as the standard, heating to 700-800 ℃ at the speed of no more than 100 ℃/hour, keeping the temperature for 1 hour, then heating to the forging temperature at the speed of no more than 120 ℃/hour, normally keeping the temperature for 1 hour, and then taking out of the furnace for forging.

4. The heating process for preheating a cold ingot by using the waste heat of the heating furnace according to claim 1, characterized in that: for group III high-alloy tool steel specified by JB/T6052-1992 standard, when the ingot type is not more than 40 tons and the diameter is not more than phi 1500mm, selecting a trolley type heating furnace with good heat preservation performance, and when the steel ingot of the previous batch is forged, the residual heat of the heating furnace is higher, and the cold ingot charging is completed by the trolley within 1 hour; after furnace loading, when the furnace temperature is higher than 950 ℃, only lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 650-900 ℃, starting to close the furnace door, not igniting at the moment, directly using the residual heat of the forged heating furnace to stew, when the instrument temperature is lower than 500 ℃, igniting again, raising the furnace temperature to 650-750 ℃, keeping the temperature for 1 hour, extinguishing the furnace, continuing to stew, repeatedly executing the process until the stew is preheated for at least 6 hours, including 1 hour of ignition at 650-750 ℃, then taking the temperature after stew as the standard, raising the temperature to 650-750 ℃ at the speed of not more than 80 ℃/hour, keeping the temperature for 1 hour, raising the temperature to the forging temperature at the speed of not more than 100 ℃/hour, and taking the furnace out of the furnace for forging after 1 hour of heat preservation.

Technical Field

The invention belongs to the technical field of forging heating, and relates to a heating process capable of reducing gas consumption and preheating a cold ingot by using waste heat of a heating furnace.

Background

At present, in the technical field of forging, steel ingots or electroslag ingots or blanks (hereinafter all referred to as steel ingots) need to be heated to a forging temperature before forging, and then the steel ingots or the blanks can be taken out of a furnace for forging, wherein two types of heating and charging are generally adopted, and one type is cold ingot charging and cold charging; the other is a hot ingot furnace; both of these are conventional heating means.

The first is annealing and slow cooling of the steel ingot after demoulding to room temperature, and then heating in a heating furnace according to a forging plan, generally in order to avoid thermal stress cracking in the heating process, according to different steel types, types and sizes of ingot types, two-section or three-section heating is needed, the first section is preheated and insulated for a certain time within the range of 400-600 ℃ according to the effective diameter of the steel ingot, the second section is heated to 650-800 ℃ and insulated for a certain time, and the third section is continuously heated to the furnace temperature during forging and insulated for a certain time, so that the core part of the steel ingot is guaranteed to be thermally penetrated and then taken out of the furnace for forging.

The second is hot ingot charging furnace, which means that the steel ingot or electroslag ingot is directly charged in a hot furnace after being demoulded, the surface temperature of the steel ingot before charging the furnace is more than or equal to 550 ℃, the heating mode generally needs to raise the temperature of the heating furnace to 650-750 ℃ or 700-800 ℃ in advance according to the type and the size of the steel for waiting for charging, and the furnace is kept warm for a period of time after charging is finished or is directly raised to the forging temperature range, kept warm for a period of time and then discharged for forging.

In actual production, in order to ensure continuous forging, after the forging of a heating furnace is finished, the temperature of the heating furnace is still above 900 ℃, if cold ingots need to be loaded, the heating furnace door needs to be lifted or a trolley needs to be pulled out, and the cold ingots can be loaded only after the temperature is reduced to below 400 ℃; the heat energy is greatly wasted, and meanwhile, the service life of the heating equipment is influenced by the heating furnace in an extremely cold and hot state.

Disclosure of Invention

The invention aims to overcome the energy waste phenomenon of cooling and then loading a cold ingot in a heating furnace during continuous production in the prior art, and provides a heating process for preheating the cold ingot by using the waste heat of the heating furnace, wherein the cold ingot is loaded at high temperature, and the heating furnace is not ignited for braising temporarily, so that the energy waste phenomenon is greatly reduced, and the fuel gas consumption in the low-temperature preheating stage during loading the cold ingot into the cooling furnace is saved.

The purpose of the invention is realized as follows:

a heating process for preheating a cold ingot by using waste heat of a heating furnace comprises the following specific process steps: selecting a heating furnace with good heat preservation, wherein the good heat preservation means that the temperature of the heating furnace is reduced by 1-5 ℃ per hour; when the residual heat of the heating furnace is high after the steel ingots of the previous batch are forged, finishing cold ingot charging within 1 hour through a trolley; after furnace charging, if the furnace temperature is higher than 950 ℃ displayed by the instrument, lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 650-950 ℃, not igniting, closing the furnace door to smolder, when the smoldering furnace temperature is lower than 500 ℃, igniting and heating to 650-750 ℃, preserving heat for 1 hour at the temperature, extinguishing again and continuing smoldering, wherein the process is repeatedly executed until the smoldering furnace is at least 6 hours and contains 1 hour of heat preservation at 650-750 ℃, starting normal ignition and heating after the smoldering furnace is preheated, and executing a normal ignition and heating process; namely, directly heating to the forging temperature at the speed of 80-150 ℃ per hour, and discharging and forging;

for the carbon steel of group I steel and the alloy structural steel in group II specified by JB/T6052-1992 standard, when the ingot type is not more than 10 tons and the diameter is not more than phi 1000mm, a trolley type heating furnace with good heat preservation performance is selected, when the steel ingot of the previous batch is forged, the residual heat of the heating furnace is higher, and the cold ingot charging is completed by the trolley within 1 hour; after furnace charging, when the furnace temperature is higher than 950 ℃, only lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 650-950 ℃, starting to close the furnace door, not igniting at the moment, directly using the residual heat of the forged heating furnace to stew, when the temperature of a stew instrument is lower than 500 ℃, starting to ignite again, raising the furnace temperature to 650-750 ℃, keeping the temperature for 1 hour, extinguishing the furnace, continuing to stew, and repeatedly executing the process until the stew furnace is preheated for at least 6 hours, and the stew furnace is kept at 650-750 ℃ for 1 hour; igniting after the annealing, directly heating to the forging temperature at the speed of not more than 150 ℃/H based on the furnace temperature after furnace closing, and taking the blank out of the furnace for forging after normal heat preservation for 1 hour.

For the carbon steel of group I steel and the alloy structural steel in group II specified by JB/T6052-1992 standard, when the ingot type meets the requirements of more than 10 tons and less than 40 tons and the diameter of a cold ingot is not more than phi 1500mm, before heating, selecting a trolley type heating furnace with good heat preservation performance, and when the forging of the steel ingot of the previous batch is finished, the residual heat of the heating furnace is higher, and the cold ingot charging is finished by the trolley within 1 hour; after furnace charging, when the furnace temperature is higher than 950 ℃, only lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 800-950 ℃, closing the furnace door to execute annealing, not igniting at the moment, directly using the residual heat of the forged heating furnace to perform annealing, when the annealing instrument temperature is lower than 500 ℃, igniting again, heating the furnace temperature to 650-750 ℃, keeping the temperature for 1 hour, extinguishing the furnace, continuing the annealing, repeatedly executing the process until the annealing is preheated for at least 6 hours, keeping the temperature for 1 hour including the ignition of 650-750 ℃, taking the temperature after the annealing as the standard, heating to 700-800 ℃ at the speed of no more than 100 ℃/hour, keeping the temperature for 1 hour, then heating to the forging temperature at the speed of no more than 120 ℃/hour, normally keeping the temperature for 1 hour, and then taking out of the furnace for forging.

For group III high-alloy tool steel specified by JB/T6052-1992 standard, when the ingot type is not more than 40 tons and the diameter is not more than phi 1500mm, selecting a trolley type heating furnace with good heat preservation performance, and when the steel ingot of the previous batch is forged, the residual heat of the heating furnace is higher, and the cold ingot charging is completed by the trolley within 1 hour; after furnace loading, when the furnace temperature is higher than 950 ℃, only lifting the furnace door to cool, not pulling out the trolley, when the furnace temperature is reduced to 650-900 ℃, starting to close the furnace door, not igniting at the moment, directly using the residual heat of the forged heating furnace to stew, when the instrument temperature is lower than 500 ℃, igniting again, raising the furnace temperature to 650-750 ℃, keeping the temperature for 1 hour, extinguishing the furnace, continuing to stew, repeatedly executing the process until the stew is preheated for at least 6 hours, including 1 hour of ignition at 650-750 ℃, then taking the temperature after stew as the standard, raising the temperature to 650-750 ℃ at the speed of not more than 80 ℃/hour, keeping the temperature for 1 hour, raising the temperature to the forging temperature at the speed of not more than 100 ℃/hour, and taking the furnace out of the furnace for forging after 1 hour of heat preservation.

The method is simple and easy to operate, and the waste heat of the forged heating furnace is utilized to convert the cold ingot into the hot ingot, so that the fuel gas consumption can be greatly reduced, and the aim of reducing the cost is fulfilled.

Drawings

FIG. 1 shows a process of heating a cold ingot in a cold furnace in example 1 of the present invention.

FIG. 2 shows a cold ingot hot furnace annealing process in example 1 of the present invention.

FIG. 3 shows a process of heating a cold ingot in a cold furnace in example 2 of the present invention.

FIG. 4 shows a cold ingot hot furnace annealing process in example 2 of the present invention.

Detailed Description

The implementation of the technical scheme of the invention mainly lies in that the heating furnace has good heat preservation performance, when in continuous production, the cold ingot is arranged and loaded after the forging of one heating furnace is finished, and the waste heat of the high-temperature furnace after forging is utilized to preheat the cold ingot without ignition or for short time ignition and smoldering furnace to be converted into a hot ingot, thereby achieving the purposes of reducing gas consumption and lowering cost.

Example 1: a heating process for preheating a cold ingot by using waste heat of a heating furnace is characterized in that the steel number is H13, the ingot type is 8 tons, and the specification of a crystallizer is as follows: the cold ingot heating example of phi 880/phi 940 illustrates that the number of gas flow meters read is 9702387 cubic meters before the braising furnace is preheated.

Selecting a trolley type heating furnace with the length, width and height of 7 m by 3 m by 2.5 m, forging at the temperature of 1230 ℃, pulling out the trolley after forging, reducing the furnace temperature to 650-900 ℃, and starting charging the ingot number as follows: 9B20618, 9A20463, 9A20464, 9A20465 and other 13 cold ingots with steel grade H13 can be completely loaded in 0.5 hour, the trolley is pulled in at the moment, the temperature displayed by the instrument is 747 ℃/750 ℃, the furnace door is closed, the braising preheating process is started, the temperature of the instrument is recorded once per hour, after the braising process is executed for 6 hours, the temperature of the two zones is basically balanced and is still 678 ℃, the braising preheating stage is not lower than 500 ℃, so that the furnace is not ignited and maintained, and the subsequent normal ignition heating part is started to be executed according to the heating process shown in FIG. 2; after the braising furnace is preheated for 6 hours, the reading gas flow bottom is still 9702387 cubic meters, and the gas is not digested in the process.

The stewing furnace is preheated for 6 hours, and the display temperatures of the instruments of the two heating zones of the trolley type heating furnace are shown in the table 1;

TABLE 1

Comparative example of example 1:

when the car-type heating furnace is a cooling furnace, 13 hours and 13 cooling ingots with the same steel number, ingot type and number as those of example 1 are selected, wherein the ingot type is 8 tons, and the specification of a crystallizer is as follows: the cold ingot with phi 880/phi 940, the ingot numbers of 8A20844, 6A20768, 6A20769, 9B20647, 9B20648, etc.; heating was performed according to the conventional heating process of fig. 1; the reading gas flow base number before heating and preheating is 12900923 cubic meters. According to the conventional heating process shown in the figure 1, firstly, igniting and heating until the temperature is 400-450 ℃ displayed by an instrument, keeping the temperature for 4.5 hours, and reading the gas flow base number of 12902232 cubic meters; the conventional process pre-heating stage therefore consumes 1309 cubic meters of fuel gas in total.

Compared with the embodiment 1, the stewing furnace preheating can save 1309 cubic meters of ignition gas consumption (compared with the cold ingot preheating stewing furnace technology, except the difference of preheating in the first stage, the rest subsequent heating speed and the heat preservation time are the same and are not compared any more).

Example 2: a heating process for preheating a cold ingot by using waste heat of a heating furnace is characterized in that three cold ingots with the steel number of 21CrMo10 and the ingot type of 19.6 tons are selected, and the steel ingot number is as follows: e2001508-1-3 is taken as an example for illustration, the effective section diameter of the steel ingot is phi 1220/phi 1125; selecting a chamber type heating furnace with the forging temperature of 1250 ℃, after forging, lifting the furnace door, reducing the furnace temperature to 800-950 ℃ of instrument display temperature, starting charging, after closing the furnace door, wherein the instrument display temperatures of two heating areas are 792 ℃/790 ℃, and the bottom number of the read gas flow is as follows: 9711365 cubic meters, starting to carry out furnace closing for 6 hours, recording the instrument temperature once per hour, preheating for 6 hours by a furnace closing, wherein the instrument display temperature in the first area is 594 ℃, the instrument display temperature in the second area is 608 ℃, the temperature in the whole furnace closing process is not lower than 500 ℃, and the temperature is not increased by ignition; the bottom of the gas flow is still 9711365 cubic meters, which shows that the preheating of the braising furnace has obvious effect on reducing the gas consumption.

In the stewing preheating stage, the display temperatures of two heating zone instruments of the chamber type heating furnace are shown in the following table 2:

TABLE 2

In the two embodiments, the surface of the steel ingot is uniformly heated after the steel ingot is discharged, and the condition that the steel ingot cracks due to thermal stress does not occur, which indicates that the heating meets the forging requirement.

Compared with the conventional cold ingot heating process, the heating mode of loading the cold ingot into the hot furnace and carrying out stewing and preheating by using the waste heat of the heating furnace is adopted, so that the ignition gas consumption (the stewing furnace does not consume gas) of low-temperature preheating in the first stage is reduced, partial gas consumption can be reduced, and the purpose of reducing the cost is achieved.